Are "urges" the source of man's suffering?

SO, I know that's a pretty grand title, and believe me, I'll get to that point. But to begin I have to explain the thought process that led me there.

I've had the idea for a while now that my life would be considerably better if I could fully control my own actions, based solely on reasonable decisions. However, this doesn't seem to be the current case. The other day, after having eaten half a pizza, I still had the other half left. I KNEW that: the calories would worsen my already burgeoning weight problem, that my girlfriend would be mad that I didn't save her dinner, and that there would be shame in my own lack of self control if I ate the pizza. I was even full, and knew that it would cause me some discomfort to carry the extra food around. But the smell of that cheese and pepperoni was too much, and I ate it anyways.

The ultimate result was worse than if I'd just put the half back in the fridge. I knew it was an unreasonable choice and that the end would be bad, but I made that decision anyways. And as an atheist, I find it very disturbing that I can't even enforce my own reason on myself. I've seen the same pattern evolve with homework, getting up in the morning, exercise, cleaning, masturbation, even things like my work. The immediate reward of procrastinating, eating, laying there, etc is overwhelmingly chosen, and I don't even usually like the outcome

I feel that if I were somehow able to force myself to make the "correct" choices, my life would be better. I'd be healthier, I'd be fit, I'd go to bed on time, I'd get better grades, I'd live in a spotless apartment, and I'd have more money. There is no question that overriding my base desires would (a vast majority of the time) improve my life.

So now I admit, the title was just to catch your eye- it is a far reaching extension of my own observations about myself. It is a bit of a reach to assume that just this is the source of "man's suffering". But I do still pose the question- how can one overcome these short term, self-destructive, basic desires, these urges, in order to undoubtedly improve your life?